372 Diseases of Greenhouse Crops 



to be four important aphids which attack plants* 

 The melon aphis (Aphis gossypii) is a general 

 feeder and attacks a large number of plants. The 

 green aphis {Nectorophora rose) seems to attack the 

 rose only. The brown aphis {Khopalosiphum viola) 

 attacks the violets. The black aphis {N ectorophora 

 chrysanthemicoleus') attacks the chrysanthemum. 

 The following table by Davis * is a list of plant 

 lice which are known to attack ornamentals in the 

 greenhouse : 



'Davis, G. C, Michigan Agr. Expt. Sta., Special Bui. 2: 5-43, 

 1896. 



